In the practice of bodybuilding, the individual strives to develop a well-defined, muscular and symmetrical body. There are many types of devices commonly employed to aid in achieving this goal. Of these devices, the free weight type, as typified by barbells and dumbbells, is the most basic. Correct use of these devices not only improves the user's muscle tone but also improves the user's balance and coordination.
Weight lifting is an isotonic exercise in which the individual contracts his or her muscles against a resistance that is moved through a range of motion. The resistance is normally in the form of a weighted object that the user moves through either a flexion or extension of his or her arms or legs.
Barbells are one of the most common devices used in weight lifting. A barbell will normally comprise a straight bar that has a medial hand grip area and weights removably received on the bar's outer ends. Some modified types of barbells employ bars with arcuate portions such as an E-Z CURL BAR. There are other modifications that have been made to the basic barbell including the use of rotatable grips and grips that can be moved against a resistance.
In weight lifting, there are a number of exercises in which the user moves a weighted barbell in order to strengthen his or her upper body muscles. One example of such an exercise is a bench press in which the individual initially assumes a supine position atop a support bench. The weight lifter then uses his or her arms to lift the barbell from a position just above the lifter's chest to a higher vertical position where the lifter's arms are fully extended. This exercise is normally accomplished without any sideways movement (abduction or adduction) of the lifter's hands. This basic exercise can be modified by inclining the support bench (inclined press) or by starting with the bar substantially coplanar with the user's torso (pull overs).
Barbells can also be employed when the lifter is in a standing position. An example of this type of exercise is the overhead or standing military press. In this exercise, the lifter uses his or her arms to lift the barbell from armpit height to a position where it is located above the lifter's head. Another type of standing exercise employing a barbell is upright rowing in which the lifter moves the barbell with his or her hands in a rowing motion.
Many exercises that can be performed with a barbell can also be performed using a pair of dumbbells. A dumbbell is basically a scaled-down version of a barbell that is designed to be grasped by a single hand of the user. The user will normally hold the dumbbells with one in each hand to perform press-type or similar exercises.
Dumbbells can also be used to perform exercises in which the user's hands are swung away or toward the centerline of the his or her body. In a dumbbell fly exercise, the abduction/adduction type of sideways arm movements function to strengthen the user's pectoral or chest muscles. For example, a female weight lifter will normally start with the dumbbells located at her side with her arms extended outward forming a "T"-shaped with her upper body. Next, she swings her arms in an arc bringing the dumbbells into a position above the centerline of her body. The dumbbells are then swung back to the original starting position.
While for many exercises barbells and dumbbells can be used interchangeably, there are certain types of exercises for which this is not the case. A barbell cannot easily be used for exercises in which abduction/adduction-type movements are required. This significantly limits the user of a barbell who wishes to strengthen his or her muscles through both a lifting and sideways arm movement. A well known advantage of a barbell is that it provides a balanced resistance to both arms at the same time. It is extremely difficult for a user of dumbbells to achieve the same balance and coordination of his or her arm muscles while using two dumbbells that are independently movable.